A novel nanomolar highly selective fluorescent probe for imaging mercury (II) in living cells and zebrafish

A novel fluorescent probe, PES, which contains a bisethylsulfane moiety, displayed high specificity for Hg²⁺ detection. With Hg²⁺, PES showed significant blue fluorescence enhancement, while the metal ions Al³⁺, Ag⁺, Cr³⁺, Ca²⁺, Cu²⁺, Co²⁺, Cd²⁺, Fe³⁺, Fe²⁺, Mn²⁺, Mg²⁺, Ni²⁺, Zn²⁺, and Pb²⁺ exhibited only negligible fluorescence change. PES has been found to be an effective quantitative detector (LOD, 57 nM) for Hg²⁺ in semi-aqueous medium based on the Hg²⁺-induced removal of bisethylsulfane. It resulted in a turn-on blue fluorescence response. The fluorescence enhancement induced by Hg²⁺ was observed over the pH range of 4–10. Our fluorescence cell-imaging experiments revealed the applicability of the new probe, PES, to be a reliable and effective fluorescent marker for Hg²⁺ in living cells.